Expulsion fuse



INVENTORS.

Nov. 9, 1943. A. G. s'rElNMAYER ETAL.

EXPULSION FUSE Filed May 14, 1942 2 Sheets-Sheet 1 NOV. 9, 1943. A. G. -sTElNMAYER E'rAL 2,334,134

EXPULSION FUSE Filed May 14, 1942 2 Sheets-Sheet 2 all TOAt/EY Patented Nov. 9, 1943 EXPULSION FUSE A'lwinG. Steinmayer and Chester W. Brown, Milwaukee, Wis., assignors to Line Material Company, South Milwaukee, Wis., a corporation of Delaware Application May 14, 194z,seria1 No. 442,922 16 clams. '('oL zoo-114) This invention relates vto expulsion fuses and is particularly directed to a housed type of expulsion fuse. Y

Objects of this invention are to provide a housed type of fuse construction in which a fuse tube and door assembly are provided, in which the door is movably supported with reference to the fuse tubejand is released upon lblowing of the fuse link so that the door may execute motion with reference to the fuse tube and unlatch the fuse tube and door assembly from the stationary portion of the apparatus, the fuse tube and door assembly thereafter rocking outwardly to open position and thereby completely removing the fuse tube from the circuit and also ,giving a visual indication that 'the fuse has blown.

Further objects of this invention are to provide a vfuse construction in which the fuse tube stays in place until the -doorunlatches fromithe housing by means of a. straight downward slicl-r ing motion with reference to the fuse tube, in which a main spring is provided for urging the door tdownwardly to unlatching position, in which the pressure of the main spring is borne by `a separate latching lever, in which this latching lever has relatively 'small inertia and quickly `extracts any remaining portionof the fuse link, in certain forms of the invention `the latching lever being `urged to unla-tching .and fuse link extracting position by means of aseparate spring, and in other forms of the invention the latching lever having a cam action with .the door to cause motion-of the latching lever either supplemented or not by means of .an auxiliary .spring acting onfthe latching lever, the object of one form of the invention being to remove all .strain of .the main spring from the fuse .link and in another form of the inventionto transmit `only a small portion v'of the force of the main spring to the fuse link.

Further objects are to provide a construction in which the main spring is located below the iowermost of the two stationary contacts and thereby does not increase the chance of arcing within the housing.

Further objects are to provide a construction in which good positive contact is provided between the contacts of the fuse Itubean'd door assembly andthe stationary contacts, in which this secure and positive contact does not impede opening ymotion of the fuse tube and door VVassembly as there is, no gripping of the contacts of the fuse tube and door assembly by the stationary contacts, but in which the stationary contacts urgethe fuse tube and door assembly towards inoperative position.

'Further objects are to provide a construction in which the motion of lthe doorwithreference to 'the fuse tube does not separate the contacts, the

movable contacts of the fusetube and door assembly remaining in engagement with the stationaryA contacts until after the combined latch.- ing and fuse'link extracting lever has executed its quick fuse extracting and unlatching motion and has been followed by downward sliding motion of the door with reference to the fuse tube, the fuse tube and y rocking outwardly to inoperative position, thus insuring complete clearing of the circuit within the fuse tube prior to separating 'the movable contacts of the fuse tube and door assembly from the stationary contacts while at the same time .securing a quick flip-out or fuse link extracting operation to quickly clear the circuit within the fuse tube.

Embodiments of the invention are shown in the accompanying drawings, in which:

Figure 1 is a view, partly in section, showing the device in operative position.'A

Figure 2 is a fragmentary sectional view of the fuse tube and door assembly removed from the housing. y Y 1 Figure 3 is a fragmentary view showing the position of the parts after the fuse tube and door assembly has moved downwardly to inoperative position.

Figure 4 is a View, partly broken away, upwardly from the bottom of Figure l. ,Y

Figure 5 is a broken away` sectional view on `the line 5-5 of Figure 1.

f Figure 6 is aA fragmentary view of a further form of the invention.

y Referring to the drawings, it will be seen that a housing I of porcelain or other suitable material is provided which has an open bottom and an open front. The open front is normally closed looking Aby means of a door 2 of a phenolic condensation compound or of other insulating material. vThe door 2 is slidably carried, as will hereinafter appear, by means'of an expulsion fuse tube 3 which is provided with an upper contact portion 4 closed by means of a screw cap 5 and which .is open at its lower end.

The housing I is provided with upper and lower terminals 6 and l to which are respectively secured lthe upper and lower` stationary contacts 8 and 9. y 4

The upper terminal also carries a bifurcated resilient latching member l0 whose arms are prodoor assembly thereafter A vided with downwardly depressed portions I' which yieldingly interlock with upwardly extending portions of a bifurcated latching member I2 carried by the door 2. The latching member I2 may or may not be resilient as desired, If desired both members Ill and I2 may be resilient, or if it is desired, only one of such members may be formed of resilient material.

It is to be noted that the fuse tube 3 extends through the lower contact I3 of the fuse tube and door assembly and may be pinned or otherwise secured thereto, as shown particularly in Figure 2. The lower contact |3 of the fuse tube and door assembly is provided with a downwardly extending portion I4 which has a pair of spaced arms I5 at its lower end, such arms being provided with outwardly extending trunnions I5 which are removably received within the hook like members I1 rigidly carried by the housing.

The door 2 is provided with a projecting sleeve like member I8 which is slidable on the fuse tube 3. This member I3 is Vpositioned between the arms I5 and is integral with the door. The door is also provided with a notched out guiding member I9 intermediate its ends which normally bears against an intermediate portion of the fuse tube and is also provided with a manipulating eyelet so that the door may be manually pulled open or may be manually closed, as by means of a switch stick for instance. g

The fuse tube and door assembly cannot be lifted from the hook supports I'I until after the fuse tube and door assembly has swung downwardly to inoperative position, for example as shown in Figure 3. v

left to thereby limit the outward motion of the latching lever,

A main spring 29 loosely surrounds the luse tube 3 and bears at its upper end against the lower contact I3 of the fuse tube and door assembly and at its other end against the sleeve like portion I8 of the door 2, thus urging the door downwardly. However, no force of the main spring 29 is transmitted to the fuse link as the latching -lever 2| positively latches beneath the lower portion of the sleeve like member I8 of the door 2. All strain on the fuse link in this form of the invention is obtained thro-ugh the medium of the auxiliary spring 23 which urges the fuse link extracting and latching lever 2| towards releasing motion.

Any tendency of upward recoil of the fuse tube l upon vblowing of the fuse link is not transmitted to the door but instead is borne by the overhanging interengagement of the hook supports I'I with the trunnions I6.

It is to be noted from an examination of Figure l that the upper and lower stationary contacts 8 and 9 bear against slanting or curved faces of the upper and lower contacts 4 and I3 of the fuse tube and door assembly and do not grip such movable contacts but instead urge the fuse tube and door assembly towards outward rocking motion about the trunnions I6. This outward rocking motion is normally resisted by the interengagement of the latching portions I0' and II.

A combined fuse link extracting and latching lever 2| is pivotally carried between a pair of bifurcated arms of the lower movable contact I3. For example it may be pivotally carried by means of a pin 22. A spring 23 is provided and urges the latching lever 2| towards the left as viewed in I Figure 1, that is to say. towards fuselink extracting and unlatching motion.

This latching lever is provided with a foot portion 24 which latches beneath the lower portion of the sleeve like part I8 ofthe door 2 and thus locks the door in its elevated position, as shown in Figure 1, until the latching lever is released upon rupture of the fuse link.

The flexible leader 25 of the fuse link extends out of the lower open-end of the fuse tube and is guided betweenvrearwardly projecting ears 26 of the combined fuse link extracting and latching lever and extends upwardly and is clamped to the lower movable Contact I3 by means of the thumb nut 2'I. The upper end of thelatching lever is provided with a projecting ear 2B, as shown in Figure 2, which is adapted to engage an adjacent face of the lower movable contact I3 when the latching lever moves outwardly to the The fuse link may be oi any suitable type and may have, for example, a reduced fusible section 30 and a buttonhead 3| which is clamped against the upper end of the upper contact 4 by means of the threaded clamping cap 5.

The operation of the apparatus is as follows: When an overload occurs, the fuse link is. ruptured and the combined latching and fuse link extracting lever 2| is released and under the influence of its auxiliary spring 23 quickly flips or pulls out any remaining portion of the fuse link, the extraction of the fuse link of course being assisted by any gas pressure that may be generated within the fuse tube. However, even with very small overload when very little gas is generated, the latching lever revertbeless Quickly pulls any remaining portion of the fuse link out of the fuse tube in a positive and effective manner. It is to be noted that although the combined fuse link extracting and latching lever has a limited stroke, nevertheless this stroke is made very quickly and considerable velocity is imparted to any remaining portion of the fuse link. This action, therefore, materially assists in clearing the circuit within the fuse tube even under light overloads and it is obvious that the clearing is assisted by the expulsive action that takes place within the vfuse tube itself. Even if the expulsive action is extremely light and the remaining portion cf the fuse link after rupture is not completely and wholly extracted from the fuse tube, it is extracted to a certain degree suilicient at least to lengthen the gap within the tube and thus assist materially in the quick clearing of the circuit even under very light overloads.

It is lto lbe noted that the combined latching and fuse link extracting lever has very little inertia and acts very quickly independently ofthe motion of any other parts of the apparatus to withdraw any remaining portion of the fuse link and thus secures rapid clearing of the circuit within the fuse tube.

After the latching lever has moved to the left, it releases the door 2 and the door then slides downwardly with reference to the fuse link, unlatching the latching members I and I0'. Thereafter the door and fuse tube as a unit rock outwardly to the position shown in Figure 3 and thus remove the fuse tube from the circuit.

It is to be noted from reference to Figure 6 that the latching lever may have a cam action with reference to the sleeve like portion I8 of the door 2. This latching lever is indicated by the reference character 2| and is provided with a cam foot 24 which has an upper slanting face engaging the lower slanting face 32 of the sleeve like member IBof the door 2. The latching lever thus has a cam action with respect to the door so that, a part of the force of the main spring 29 is transmitted to the latching and fuse link extracting lever 2l and causes the .fuse link extreating and latching lever to move to unlatching position upon rupture of the fuse link. If desired, in this form of the invention an auxiliary spring corresponding tothe spring 23 may be employed. In other words,where the cam action is utilized, it may be utilized independently of an auxiliary springy or with an auxiliary spring as desired. Even when a cam action is employed. the parts are so designed that very little of the force from the main spring is transmittedto the fuse link. However, in the form of the invention shown in Figure 1,'no force from the main spring is transmitted to the fuse link.

It will be seen that the force of the main spring is in all forms of `theinvention borne by a latching lever. In the first form of the invention no force of the main spring is transmitted to the latching lever and in other forms of the invention a small fraction of the force of the main spring is transmitted to the latching lever. In all forms of the invention itwill be seen that a latching lever having verysmall inertia has been provided, that this latching lever moves with a quick motion to extract any remaining portion of the fuse link and assist in the quick clearing of the circuit within the fuse tube, and that after the latching lever has executed its motion the door moves downwardly and unlatches the fuse g tube and door assembly. At this time the movable contacts of the fuse tube and door assembly move away from the stationary contacts of the housing. This construction, therefore, insures complete and quick clearing of the circuit Within g the fuse tube prior to opening of the fuse tube and door assembly. It will be seen further that very simple types of contacts can be employed, that no gripping occurs between the stationary contacts of the housing and the movable contacts of the fuse tube and door assembly, but nevertheless a very irm and adequate contact is obtained.

Although this invention has been describedin considerable detail, it is to be understood that such description is intended as illustrative rather than limiting as the invention may be variously embodied and is to be interpreted as claimed.v l We claim:

l. A housed type fuse comprising a housing,` a fuse tube pivotally supported from said housing, a door movable with respect to said tube and normally removably locked to said housing, a latcliing lever normally directly engaging and latohing said door against motion with respect to said tube, and a fuse link carried by .said fuse tube and restraining said door against motion with respect to said fuse tube.

2. A housed typefuse comprising a housing, a

fuse tube pivotally supported from ysaid housing,

a door slidably mounted on said tube and nor-- mally removably locked to said housing, a latching lever normally latching said door against sliding motion with respect to said tube, and a fuse link carried by said fuse tube and restrain- `ing said door against .motion with respect to said fuse tube.

3. A housed type fuse comprising a housing, a `fuse tube pivotally supported from said housing,

a door slidably mounted on said fuse tube, a

spring urging said door ltowards sliding motion, said door and .said `housing having normally interlocking members releasable when said door slides with respect rto said ifuse tube, a fuse link carried bysaid fusetube and projecting outwardly 3 from said fuse tube, and a latchng lever` pivotal!! supported from said fuse tube and normalb latching said door against sliding motion, and latching lever being restrained by said fuse link and releasing said door upon rupture of said fuse link.

4. A housed type fuse comprising a housing having an open front and an open bottom, a door normally closing the open front, afuse tube `normally housed within and pivotally supported from said housing and having an open lower end adjacent the open bottom of said housing, a fuse link within said fuse tube and projecting outwardly from the open lower end of said fuse tube, said door being slidablymounted on said fuse tube, locking means `normally locking saiddoor and fuse tube against outward pivotal motion and releasable when said door slides with reference to said fuse tube, and latching means movable independently of .said door for normally restraining said door against sliding motion with respect to said `fuse tube, said latching means being controlled by the outwardly projecting portion vof said fuse link and being released upon rupture of said fuse link. i

5. A housed type fuse comprising a housing having an open front, a` door normally closing said open front, a fuse tube normally housed Within and pivotally supported from said housing,

`said door being slidably mounted on said fuse tube, a spring urging said door towards sliding motion with reference to said fuse tube, said housing and said door having interlocking means releasable when said `door slides with reference to said fuse tube, latching means movable independently `ci? said door for normally restraining said door against sliding motion with respect to said fuse tube. said Vlatching means being biased towards releasing motion, and a fuse link carried by said `fuse tube and normally restraining said latching means, said latching means being released upon rupture of said fuse link, said fuse link being free of any stress -due to the force exerted by said spring.

6. A housed type Afuse comprising ,a housing having an open front, a door normally closing ysaid open front, a fuse tube normally housed within and pivotally supported from said housing, l.said `door being slidably mounted on lsaid fuse tube, a spring urging said door towards sliding motion with reference to said fuse tube, said housing and .said door having interlocking means releasablewhen said door slides with reference to said fuse tube, latching means movable independently of said door for normally restraining said door against sliding motion with ,respect to fuse tube, said latchin'g `means being biased towards rrdeasing motion, and a fuse link carried by .said fuse tube and normally restraining said latching means, said latching means 4being released upon rupture of said fuse link` said latch-.- means transmitting a portion of the stress .of said spring to said fuse link.

'7. A housed type fuse comprising a housing, a door for said housing normally interlocking with said 'housing and releasable upon motion of said door longitudinally of said housing, a iuse tube pivotally` supported from said housing and normally housed within said housing yand slidably supporting said door, a main spring urging said ldoor towards sliding motion with reference to said fuse tube, a fuse link within said fuse tube, a pivotaliy supported latching lever normally latching said door against sliding motion with reference to said fuse tube, said latching lever 'being controlled by said fuse link, and an auxiliary spring urging said latching lever towards releasing motion.

8. A housed type fuse comprising a housing, a door for said housing normally interlocking with said housing and releasable upon motion of said door longitudinally of said housing, a fuse tube pivotally supported from said housing and normally housed within said housing and slidably supporting said door, a main spring urging said door towards sliding motion with reference to said fuse tube, a fuse link within said fuse tube, a pivotally supported latching lever normally latching said door against sliding motion with reference to said fuse tube, said latching lever being controlled by said fuse link, and an auxiliary spring urging said latching lever towards releasing motion, said fuse link being free from any stress due to said main spring.

9. A housed type fuse comprising a housing, a door for said'housing normally interlocking with said housing and releasable upon motion of said door longitudinally of said housing, a fuse tube pivotally supported from said housing and normally housed within said housing and slidably supporting said door, a main spring urging said door towards sliding motion with reference to said fuse tube, a fuse link within said fuse tube, a pivotally supported latching lever normally latching said door against sliding motion with reference to said fuse tube, said latching lever being controlled by said fuse link, and an auxiliary spring urging said latching lever towards releasing motion, said latching lever and said door having a cam action, whereby a part of the stress from said main spring is transmitted to said fuse link.

10. A housed type of fuse comprising a housing having an open front, a fuse tube normally mounted within said housing, means pivotally supporting said fuse tube from said housing, a door normally closing the open front of said housing. said door being slidably guided by said fuse tube and being biased towards sliding motion with respect to said fuse tube, interengaging locking means carried jointly by said housing and said door and detachable when said door slides with reference to said fuse tube, whereby said door and fuse tube can rock outwardly from said housing as a unit upon release of said interengaging locking means, a fuse link within said'fuse tube, and a latching lever biased towards releasing motion and controlled by said fuse link for normally latching said door against sliding motion with respect to said fuse tube.

1l. A housed type of fuse comprising a housing having a pair of stationary contacts, a fuse tube having spaced contacts normally engaging said stationary contacts, said fuse tube being pivoted within said housing, a fuse link joining the spaced contacts of said fuse tube, a door slidably mounted on said fuse tube and spring urged towards sliding motion with respect to said fuse tube, and latching means movable independently of said door for latching said door against sliding motion with respect to said fuse tube, said latching means being controlled by said fuse link.

l2. A housed type oi fuse comprising'a housing having a pair of stationary contacts, a fuse tube having spaced contacts normally engaging said stationary contacts, said fuse tube being pivoted within said housing, a fuse link joining the spaced contacts of said fuse tube, a door slidably mounted on said fuse tube and spring urged towards sliding motion with respect to said fuse tube, and latching means movable independently of said door for latching said door against sliding motion with respect to said fuse tube, said latching means being controlled by said fuse link, said door and said fuse tube being biased towards outward swinging motion with respect to said housing.

13. A housed type of fuse comprising a housing having a pair of stationary contacts, a fuse tube having spaced contacts normally engaging said stationary contacts, said fuse tube being pivoted within said housing, a fuse link joining the spaced contacts of said fuse tube, a door slidably mounted on said fuse tube and spring urged towards sliding motion with respect to said fuse tube, a latching lever pivotally mounted on one of the spaced contacts of said fuse tube for latching said door against sliding motion with respect to said fuse tube, said latching lever being controlled by said fuse link and releasing said door upon rupture of said fuse link, said door and fuse tube being biased towards outward rocking motion with respect to said housing.

14. A housed type of fuse comprising a housing having an open front, a fuse tube pivotally mounted within said housing, said housing having stationary contacts and said fuse tube having spaced contacts normally engaging said stationary contacts, a fuse link within said fuse tube connecting the spaced contacts of said fuse tube, a door slidably mounted on said fuse tube, a latching lever pivotally mounted on one of the spaced contacts of said fuse tube' for normally latching said door against sliding motion with respect to said fuse tube, a main spring surrounding said fuse tube and urging said door towards sliding motion, and an auxiliary spring urging said latching lever towards releasing motion, said latching lever being controlled by said fuse link,

15. A housed type of fuse comprising a, housing, a door for said housing, saidhousing having upper and lower stationary contacts, a fuse tube having upper and lower contacts normally engaging the upper and lower stationary contacts, a fuse link carried within said fuse tube and normally connecting the contacts of said fuse tube, a spring surrounding said fuse tube and located below the lower stationary Contact for urging said door towards sliding motion with respect to said fuse tube, said door being normally detachably interlocked with respectto said housing and being released upon sliding motion of said door, and means controlled by said fuse link for restraining said door against sliding motion.

16. A housed type of fuse comprising a housing, a door for said housing, said housing having upper and lower stationary contacts, a fuse tube having upper and lower contacts vnormally engaging the upper and lower stationary contacts, said fuse tube being pivotally mounted within said housing, a fuse link carried within said fuse tube and normally connecting the contacts of said fuse tube, a spring surrounding said fuse tube and located below the lower stationary contact for urging said door towards sliding motion with respect to said fuse tube, said door being normally detachably interlocked with respect to said housing and being released upon sliding motion of said door, and means controlled by fuse link for restraining said door against sliding motion, said stationary contacts biasing said door and fuse tube towards outward swinging motion.

ALWIN G. STEINMAYER. CHESTER `W. BROWN. 

